The present invention relates to an absorbent article, such as a diaper, pant diaper, incontinence guard, sanitary napkin, wound dressing and the like, of the kind comprising a liquid pervious top layer, a liquid impervious back layer and an absorbent body arranged therebetween.
Absorbent articles of the above-mentioned kind are intended for absorption of body fluids, such as urine and blood. As a liquid pervious topsheet, facing the wearer during use, they usually exhibit a nonwoven material, for example of spunbond-type. It is also previously known to arrange a liquid acquisition layer between the top layer and the absorbent body, said liquid acquisition layer having the ability to quickly receive large quantities of liquid, and to distribute the liquid and temporarily store it before it is absorbed by the underlying absorbent body. This is of great importance, especially in the thin compressed absorbent bodies of today, often comprising a high content of so called superabsorbents, which certainly have a high absorption capacity but in many cases a too low absorption rate in order to momentously be able to absorb the large quantity of liquid which can be discharged within a few seconds during urination. A porous, relatively thick acquisition layer, for example in the form of a fibrous wadding, a carded fibrous web, or another type of fibrous material, has a high instantaneous liquid-receiving capacity and is able to store the liquid temporarily until it has been absorbed by the absorbent body. The same applies for porous foam materials. The liquid is thereafter drained successively into the adjacent absorbent body, after which the acquisition layer once again has the capacity to receive liquid from a repeated wetting.
Examples of absorbent articles comprising such porous acquisition layers are, for example, disclosed in U.S. Pat. No. 3,371,667, EP-A-0,312,118 and EP-A-0,474,777.
The materials used today as acquisition layers in absorbent articles are mostly functioning well, but are relatively expensive and can sometimes exhibit an insufficient acquisition rate, especially in the second and third wettings, if large quantities of liquid are involved. Furthermore, they are difficult to process and store due to their bulkiness.
It is previously known through EP-A-0,391,814 and GB-B-2,209,672 to use continuous, unbonded synthetic fibres, so-called tow, in absorbent articles for distributing liquid in the longitudinal direction of the article.
Another problem is that conventional liquid pervious topsheet materials used for absorbent articles of this kind, normally a nonwoven material of synthetic fibres, e.g. a spunbond material, often exhibit a lower acquisition rate for liquid than the acquisition layer, wherein liquid can leak out from the article before it reaches the acquisition layer. Furthermore, the liquid is retained in capillaries in a dense topsheet of nonwoven and a more porous acquisition layer, e.g. wadding, cannot drain liquid from the topsheet. This problem can of course be solved by means of using a topsheet material which is very open and therefore has a high liquid permeability. Such an open topsheet material can, however, cause problems with too low strength and sharp fibre ends from the acquisition layer which may penetrate the open topsheet material and irritate the user.
The object of the present invention is to provide a material which exhibits a high acquisition rate for liquid also when repeatedly wetted, exhibits a high strength and wear resistance, high comfort, high processability and has a relatively low price. Furthermore, it should be possible to combine different wishes, concerning the liquid acquiring and liquid distributing properties, in the same material. According to the invention, this has been achieved by means of a layer of continuous fibres, so-called tow, which have been bonded together in points, lines or spots in a bonding pattern, but otherwise are substantially unbonded to each other, wherein the bonding pattern is different in different portions of said layer.
According to a preferred embodiment, the bonding pattern is more sparse in the central portion of the layer, intended to constitute the liquid acquisition area of the article, and denser in one or several of the edge portions of the layer. Thereby, a rapid liquid acquisition can be obtained in the central portions of the layer, while liquid leakage from the edge portions of the layer is rendered more difficult.
Furthermore, since the liquid distributing ability of the material in the longitudinal direction of the fibres is very high, it is advantageous if the bonding pattern, along the transversely to the longitudinal direction of the continuous fibres extending edge portions of the article, exhibits a high density which essentially prevents liquid from spreading, whereby edge leakage can be prevented.
Preferably, the bonding pattern in said transversely extending edge portion comprises at least one continuous barrier line which prevents liquid from spreading.
According to a preferred embodiment, the bonding pattern along the encompassing edge portions of the layer exhibit a high density, which essentially prevents liquid from spreading, and according to still another embodiment, the bonding pattern exhibits at least one continuous barrier line in said encompassing edge portion which prevents liquid from spreading.
Furthermore, the layer can exhibit one or several continuous directing lines intended to achieve a controlled liquid distribution in the layer.
The bonding pattern may further be designed so that the layer obtains a three-dimensional shape, for example a bowl-shape or a raised central portion.
The bonding pattern is preferably non-random.
The layer can be used as a liquid acquisition layer underneath a topsheet, as a topsheet, or as an integrated topsheet/liquid acquisition layer.
Further features of the invention are evident from the following description and the claims.